On 11/07/2024 06:12, Nitin Gote wrote:
We're seeing a GPU HANG issue on a CHV platform, which was caused by
bac24f59f454 ("drm/i915/execlists: Enable coarse preemption boundaries for gen8").
Gen8 platform has only timeslice and doesn't support a preemption mechanism
as engines do not have a preemption timer and doesn't send an irq if the
preemption timeout expires. So, add a fix to not consider preemption
during dequeuing for gen8 platforms.
Also move can_preemt() above need_preempt() function to resolve implicit
declaration of function ‘can_preempt' error and make can_preempt()
function param as const to resolve error: passing argument 1 of
‘can_preempt’ discards ‘const’ qualifier from the pointer target type.
v2: Simplify can_preemt() function (Tvrtko Ursulin)
Yeah sorry for that yesterday when I thought gen8 emit bb was dead code,
somehow I thought there was a gen9 emit_bb flavour. Looks like I
confused it with something else.
Fixes: bac24f59f454 ("drm/i915/execlists: Enable coarse preemption boundaries for gen8")
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11396
Suggested-by: Andi Shyti <andi.shyti@xxxxxxxxx>
Signed-off-by: Nitin Gote <nitin.r.gote@xxxxxxxxx>
Cc: Chris Wilson <chris.p.wilson@xxxxxxxxxxxxxxx>
CC: <stable@xxxxxxxxxxxxxxx> # v5.2+
---
.../drm/i915/gt/intel_execlists_submission.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 21829439e686..59885d7721e4 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -294,11 +294,19 @@ static int virtual_prio(const struct intel_engine_execlists *el)
return rb ? rb_entry(rb, struct ve_node, rb)->prio : INT_MIN;
}
+static bool can_preempt(const struct intel_engine_cs *engine)
+{
+ return GRAPHICS_VER(engine->i915) > 8;
+}
+
static bool need_preempt(const struct intel_engine_cs *engine,
const struct i915_request *rq)
{
int last_prio;
+ if (!can_preempt(engine))
+ return false;
+
if (!intel_engine_has_semaphores(engine))
Patch looks clean now. Hmmm one new observation is whether the "has
semaphores" check is now redundant? Looks preemption depends on
semaphore support in logical_ring_default_vfuncs().
Regards,
Tvrtko
return false;
@@ -3313,15 +3321,6 @@ static void remove_from_engine(struct i915_request *rq)
i915_request_notify_execute_cb_imm(rq);
}
-static bool can_preempt(struct intel_engine_cs *engine)
-{
- if (GRAPHICS_VER(engine->i915) > 8)
- return true;
-
- /* GPGPU on bdw requires extra w/a; not implemented */
- return engine->class != RENDER_CLASS;
-}
-
static void kick_execlists(const struct i915_request *rq, int prio)
{
struct intel_engine_cs *engine = rq->engine;
